Pulse-Based Writing for Magnetic Storage Media

ABSTRACT

The present disclosure describes aspects of pulse-based writing for magnetic storage media. In some aspects, a pulse-based writer of magnetic storage media determines that a string of data bits having a same polarity corresponds to a magnet longer than a threshold associated with a magnetic media writer. The pulse-based writer inserts, into the string of data bits, a transition to a polarity opposite to the same polarity of the string of data bits. The string of data bits including the inserted transition is then transmitted to the magnetic media writer to cause a write head of the writer to pulse while writing the magnet to magnetic storage media. Various aspects may also implement a control signal to mask a transition or control polarity of the magnetic media writer. By so doing, magnets may be written to the magnetic storage media more efficiently or with less distortion to neighboring tracks.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of and claims priority to U.S.Utility patent application Ser. No. 17/234,557, filed Apr. 19, 2021,which in turn claims priority to U.S. Utility patent application Ser.No. 16/928,971, filed Jul. 14, 2020, which in turn claims priority toU.S. Utility patent application Ser. No. 16/545,966, filed Aug. 20,2019, which in turn claims priority to U.S. Provisional PatentApplication Ser. No. 62/720,791, filed Aug. 21, 2018, the disclosures ofwhich are incorporated by reference herein in their entireties.

BACKGROUND

Electronic devices provide many services to modern society. Theseservices enable an electronic device to provide entertainment, assistwith scientific research and development, and provide many modern-dayconveniences. Many of these services create or use data, which theelectronic device stores. This data may include digital media such asbooks or movies, algorithms that execute complex simulations, personaluser data, applications, and so forth. To avoid exceeding data storagelimits, it is beneficial to increase the data storage capacity of theelectronic device and avoid deleting data, limiting services, orpurchasing additional external storage devices.

Many electronic devices use media drives to store data on disks, such asa hard-disk drive. Generally, the data of each disk is organized alongconcentric tracks of magnetic media in which individual bits of the dataare written. To accommodate greater amounts of user data, data densitiesper media disk have increased substantially, shrinking physicalgeometries of both the tracks and bits written on the magnetic media. Insome cases, track and bit sizes have shrunk such that a write head of ahard-disk drive is much larger than the individual data bits it writeson the magnetic media of the disk. The larger relative size of the writehead can cause issues when writing magnets to the storage media,particularly when current of the write head ramps up and remains at ahigh level to write long magnets, such as for a string of consecutiveones or zeros. This not only consumes extra power to continuously orrepeatedly overwrite magnet portions with a same polarity but can alsodegrade data bits of neighboring tracks with excess magnetic fieldsinduced by the continuously applied write current.

SUMMARY

This summary is provided to introduce subject matter that is furtherdescribed in the Detailed Description and Drawings. Accordingly, thisSummary should not be considered to describe essential features nor usedto limit the scope of the claimed subject matter.

In some aspects, a pulse-based writer of magnetic storage mediaimplements a method that determines that a string of data bits having asame polarity corresponds to a magnet longer than a threshold associatedwith a magnetic media writer. The method includes inserting, into thestring of data bits, at least one transition to a polarity opposite tothe same polarity of the string of data bits. The method then transmits,to the magnetic media writer, the string of data bits including the atleast one transition to cause a write head of the writer to pulse whilewriting the magnet corresponding to the string of bits. By so doing, thepulse-based writer may write magnets (e.g., long magnets) to themagnetic storage media more efficiently and with less degradation todata bits written on neighboring tracks of the magnetic storage media.

In other aspects, an apparatus comprises an interface to receive datafrom a host, a disk of magnetic storage media to store the data, amagnetic media writer configured to write the data to the magneticstorage media as data bits, and a pulse-based writer. The pulse-basedwriter is configured to determine that a string of the data bits havinga same polarity corresponds to a magnet longer than a thresholdassociated with the magnetic media writer. The pulse-based writerinserts, into the string of the data bits, at least one transition to apolarity opposite to the same polarity of the string of the data bits.The string of the data bits, including the at least one transition, istransmitted by the pulse-based writer to the magnetic media writer tocause a write head of the writer to pulse while writing the magnet tothe magnetic storage media of the disk.

In yet other aspects, a System-on-Chip (SoC) is described that includesan interface to a host from which data is received, an interface to amagnetic media writer of the magnetic storage media, and a pulse-basedwriter that is implemented at least partially in hardware. Thepulse-based writer configured to determine that a string of data bitshaving a same polarity corresponds to a magnet longer than a thresholdassociated with the magnetic media writer. The pulse-based writerinserts, into the string of data bits, at least one transition to apolarity opposite to the same polarity of the string of data bits. Thepulse-based writer then transmits, to the magnetic media writer, thestring of data bits including the at least one transition to cause awrite head of the magnetic media writer to pulse while writing themagnet to the magnetic storage media.

The details of one or more implementations are set forth in theaccompanying drawings and the following description. Other features andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of one or more implementations of pulse-based writing formagnetic storage media are set forth in the accompanying figures and thedetailed description below. In the figures, the left-most digit of areference number identifies the figure in which the reference numberfirst appears. The use of the same reference numbers in differentinstances in the description and the figures indicates like elements:

FIG. 1 illustrates an example operating environment having devices inwhich magnetic storage media is implemented in accordance with one ormore aspects.

FIG. 2 illustrates an example configuration of the hard-disk drive shownin FIG. 1.

FIG. 3 illustrates example configurations of a read/write channel andpre-amplifier in accordance with one or more aspects of pulse-basedwriting.

FIG. 4 depicts an example method for implementing pulse-based writingfor magnetic storage media in accordance with one or more aspects.

FIG. 5 illustrates an example graph of pre-amp data that includestransitions in accordance with one or more aspects.

FIG. 6 illustrates another example graph of pre-amp data that includestransitions in accordance with one or more aspects.

FIG. 7 depicts an example method for pulse-based writing with polaritycontrol.

FIG. 8 illustrates example graphs of pre-amp data and a control signalfor polarity control in accordance with one or more aspects.

FIG. 9 depicts an example method for pulse-based writing based on acontrol signal.

FIG. 10 illustrates an example graph of a control signal for pulse-basedwriting in accordance with one or more aspects.

FIG. 11 depicts an example method for relaxing write current of amagnetic media writer.

FIG. 12 illustrates an example graph of a control signal useful to relaxwrite current in accordance with one or more aspects.

FIG. 13 depicts an example method for relaxing write current withtransitions inserted in pre-amp data.

FIG. 14 illustrates an example graph of pre-amp data that includestransitions in accordance with one or more aspects.

FIG. 15 illustrates an example System-on-Chip (SoC) environment forimplementing aspects of pulse-based writing for magnetic storage media.

FIG. 16 illustrates an example storage media controller configured toimplement aspects of pulse-based writing in magnetic media with whichthe controller is associated.

DETAILED DESCRIPTION

Conventional techniques for writing data to magnetic media of a diskoften provide continuous current of one polarity or another to a writehead by which the data is written to the magnetic media. Generally, thedata of each disk is organized along concentric tracks of magnetic mediain which individual bits of the data are written. As data densities permedia disk have increased substantially, the physical geometries of boththe tracks and bits written on the magnetic media have shrunk. Withcurrent drive technology, the write head of a hard-disk drive istypically much larger than the individual data bits it writes on themagnetic media of the disk. The larger relative size of the write headcan cause issues when writing magnets to the storage media, particularlywhen the continuous current of the write head ramps up to one polarityand remains at a high level to write long magnets, such as for a stringof consecutive ones or zeros. This not only consumes extra power tocontinuously or repeatedly overwrite magnet portions with a samepolarity but can also degrade data bits of neighboring tracks withexcess magnetic fields induced by the continuously applied writecurrent.

This disclosure describes apparatuses and techniques of pulse-basedwriting for magnetic storage media. In contrast with conventional magnetwriting techniques, the described apparatuses and techniques mayimplement pulse-based writing in which current of a magnetic media writehead may be pulsed, such as based on bit transitions or control signals,to more efficiently write magnets or reduce distortion of data inneighboring tracks. For example, a magnetic media write head istypically longer than a length of an individual bit, e.g., lineardensity in magnetic recording is approaching 2500 kbpi (kilo-bits perinch), which means a size of an individual bit is on the order of 10nanometers (10 nm). In contrast, a footprint or effective length of thewrite head may be significantly longer, e.g. 60 nm. Due to thisdifference in size, when the write head (media writer) has a particularmagnetization polarity, it often magnetizes an area under the write headthat corresponds to several data bits according to this polarity. Inother words, the write head writes, during or in each bit period, thearea of 4-6 consecutive bits with the one polarity as ones or zeros.

Because of this, aspects of pulse-based writing may permit the mediawriter to forgo or avoid providing additional magnetic field once themedia has been magnetized to the desired polarity. As such, pulse-basedwriting for magnetic storage media may enable more efficient writing byreducing (e.g., relaxing) or turning off the write current provided to awrite head. In various aspects of pulse-based writing, a pulse-basedwriter may provide write current to, or a magnetic field at, a writehead for a short duration of time when a transition in the magneticfield is desired to alter a polarization of the magnetic media. Forexample, if a total length of consecutive bits having a same polarityexceeds a threshold or the length of the write head, then an additionalpulse may be added or implemented at the write head to magnetizemagnetic media that was not magnetized by the previous pulse (e.g., at astart of the consecutive bits).

With respect to write head geometry, the footprint of the write head maybe on the order of 4-6 bits long, therefore able to write one bit (1T—Tbeing a period of time to write a single bit magnet) or four bits (4T)with the same amount of current or effort. That is, once the first bitis written at the trailing edge of the write head, the write head hasalready written four bits (4T) of magnet or a longer magnet on themagnetic media under the write head. As such, a single pulse of writecurrent is often sufficient to generate magnets of four to six bits(4T-6T) length and less. In other words, a single pulse of current orwrite field may be sufficient to write 4T and shorter magnets, withadditional pulses enabling the writing of longer magnets. For example,providing a pulse of current or write field every 4T or 6T may enablethe writing of longer magnets, such as for long strings of ones orzeroes in write data.

Generally, a read/write channel (or “read channel”) of a magnetic mediadrive provides, to a pre-amplifier of the drive, a signal correspondingto a data pattern intended for writing on the media. The pre-amplifier(or pre-amp) circuit then generates or provides a write current to awrite head of the media drive with a pattern of polarity correspondingto the data pattern. Based on the signal pattern provided by the readchannel, the pre-amplifier changes the polarity of the write currentthat is sent to the write head. The pre-amplifier may also provide anovershoot current at or proximate to polarity changes to quicken achange of magnetic field of the write head. In aspects of pulse-basedwriting, a write mode may be enabled by which write current is providedas a pulse of current or over-shoot current on these transitions (orseries of current pulses to write long or different polarity magnets).

In aspects of pulse-based writing, a pulse-based writer implemented withthe read channel and/or pre-amp circuitry may manage the write currentprovided to a write head to implement pulse-based writing and/or currentrelaxation. In some cases, the pre-amp may effectively turn off thewrite current (e.g., I_(w) or steady-state write current) afterproviding a pulse of overshoot write current (e.g., I_(w)+OSA or I_(w)plus overshoot). To enable an aspect of pulse-based writing, pulsingaway from transitions in a data pattern may be facilitated by injectingtwo transitions (e.g., fake transitions or a fake bit(s)) in signalingprovided by the read channel to pre-amp, with an additional controlsignal to indicate to the pre-amp to inhibit or prevent pulsing when thecontrol signal is active (e.g., high).

In other words, if the control signal is high, the pre-amp does notgenerate a write pulse, which enables the generation of multiple (e.g.,periodic) pulses for long magnets. For example, for a first transition,the pulse-based writer may assert the control signal high (to prevent apulse on the leading transition) and deassert the control signal low forthe second transition to provide or generate a pulse of a same polarityof a preceding pulse (e.g., a pulse at a start of the magnet) at thesecond transition. Alternately or additionally, if the pre-amp isimplemented with a memory, then consecutive pulses of a same polaritymay have lower amplitude, and as such, the pre-amp would need to knowits state (e.g., to compensate for the lower amplitude with overshoot).

Some aspects described in this disclosure may also include write currentrelaxation which may turn off or set write current to a pre-bias state(non-I_(w) state). In some cases, the write current or magnetic field(write field) is turned off towards or proximate to the end of a longmagnet written (e.g., consecutive bits written with a same polarity) tothe magnetic storage media. For example, if 10 consecutive bits (10T)are written with the same polarity, then the magnetic field may beapplied for a duration (or pulsed) for the first five or six bits(5T-6T), and then the write field may be relaxed or reduced to 0 or apre-bias state (e.g., for a next transition). Because the full 10T ofbits are written by the fifth or sixth bit, due to write head size, thewrite field is no longer needed to write the last four or five bits(4T-5T). By so doing, the magnetic media writer may be prepared (e.g.,avoiding a full positive to negative write current swing) for atransition to opposite polarity, thus providing a faster or cleanertransition on a next magnet. Alternately or additionally, anotherbenefit of write current relaxation and pulse-based writing is that themagnetic field is not applied when the magnetic field is not needed(e.g., for long magnets), and this may in turn reduce the effect themagnetic field has on previously written data on neighboring datatracks, such as reduced degradation or distortion.

In various aspects of pulse-based writing for magnetic storage media, apulse-based writer may determine that a string of data bits having asame polarity corresponds to a magnet longer than a threshold associatedwith a magnetic media writer. The pulse-based writer inserts, into thestring of data bits, a transition to a polarity opposite to the samepolarity of the string of data bits. The string of data bits includingthe inserted transition is then transmitted to the magnetic media writerto cause a write head of the magnetic media writer to pulse whilewriting the magnet to magnetic storage media. Various aspects may alsoimplement a control signal to mask a transition or provide an indicationof signal polarity of the magnetic media writer. By so doing, thepulse-based writer may write magnets (e.g., long magnets or magnets thatexceed write head dimensions) to the magnetic storage media moreefficiently and with less degradation to data bits written onneighboring tracks.

The following discussion describes an operating environment, techniquesthat may be employed in the operating environment, and a System-on-Chip(SoC) in which components of the operating environment can be embodied.In the context of the present disclosure, reference is made to theoperating environment by way of example only.

Operating Environment

FIG. 1 illustrates an example operating environment 100 having acomputing device 102, capable of storing or accessing various forms ofdata or information. Examples of a computing device 102 may include alaptop computer 104, desktop computer 106, and server 108, any of whichmay be configured as part of a storage network or cloud storage. Furtherexamples of a computing device 102 (not shown) may include a tabletcomputer, a set-top-box, a data storage appliance, wearablesmart-device, television, content-streaming device, high-definitionmultimedia interface (HDMI) media stick, smart appliance, homeautomation controller, smart thermostat, Internet-of-Things (IoT)device, mobile-internet device (MID), a network-attached-storage (NAS)drive, aggregate storage system, gaming console, automotiveentertainment device, automotive computing system, automotive controlmodule (e.g., engine or power train control module), and so on.

Generally, the computing device 102 may provide, communicate, or storedata for any suitable purpose, such as to enable functionalities of aparticular type of device, provide a user interface, enable networkaccess, implement gaming applications, playback media, providenavigation, edit content, provide data storage, or the like. Alternatelyor additionally, the computing device 102 is capable of storing variousdata, such as databases, user data, multimedia, applications, operatingsystems, and the like. One or more computing devices 102 may beconfigured to provide remote data storage or services, such as cloudstorage, archiving, backup, client services, records retention, and soon.

The computing device 102 includes a processor 110 and computer-readablestorage media 112. The processor 110 may be implemented as any suitabletype or number of processors, either single-core or multi-core (e.g.,ARM or x86 processor cores), for executing instructions or commands ofan operating system or other programs of the computing device 102. Thecomputer-readable storage media 112 (CRM 112) includes memory media 114and a media drive 116. The memory media or system memory of thecomputing device 102 may include any suitable type or combination ofvolatile memory or nonvolatile memory. For example, volatile memory ofthe computing device 102 may include various types of random-accessmemory (RAM), dynamic RAM (DRAM), static RAM (SRAM) or the like. Thenon-volatile memory may include read-only memory (ROM), electronicallyerasable programmable ROM (EEPROM) or Flash memory (e.g., NOR Flash orNAND Flash). These memories, individually or in combination, may storedata associated with applications and/or an operating system ofcomputing device 102.

The media drive 116 of the computing device 102 may include one or moremedia drives or be implemented as part of a data storage system withwhich the computing device 102 is associated. In this example, the mediadrive 116 includes a hard-disk drive 118 (HDD 118), which is capable ofstoring data and is described with reference to various aspects ofpulse-based writing. Alternately or additionally, the media drive 116may be configured as any suitable type of data storage drive or system,such as a storage device, storage drive, storage array, storage volume,or the like. Although described with reference to the computing device102, the media drive 116 may also be implemented separately as astandalone device or as part of a larger storage collective, such as adata center, server farm, or virtualized storage system (e.g., forcloud-based storage or services) in which aspects of pulse-based writingare implemented.

The computing device 102 may also include I/O ports 120, a graphicsprocessing unit (GPU, not shown), and data interfaces 122. Generally,the I/O ports 120 allow a computing device 102 to interact with otherdevices, peripherals, or users. For example, the I/O ports 120 mayinclude or be coupled with a universal serial bus, human interfacedevices, audio inputs, audio outputs, or the like. The GPU processes andrenders graphics-related data for computing device 102, such as userinterface elements of an operating system, applications, or the like. Insome cases, the GPU accesses a portion of local memory to rendergraphics or includes dedicated memory for rendering graphics (e.g.,video RAM) of the computing device 102.

The data interfaces 122 of the computing device 102 provide connectivityto one or more networks and other devices connected to those networks.The data interfaces 122 may include wired interfaces, such as Ethernetor fiber optic interfaces for data communicated over a local network,intranet, or the Internet. Alternately or additionally, the datainterfaces 122 may include wireless interfaces that facilitatecommunication over wireless networks, such as wireless LANs, wide-areawireless networks (e.g., cellular networks), and/or wirelesspersonal-area-networks (WPANs). Any of the data communicated through theI/O ports 120 or the data interfaces 122 may be written to or read fromthe storage system of the computing device 102 in accordance with one ormore aspects of pulse-based writing for magnetic storage media.

Returning to the media drive 116, the computing device 102 may includethe hard-disk drive 118 as shown and/or other types of storage media onwhich pulse-based writing may be implemented. Although not shown, otherconfigurations of the media drive 116 are also contemplated, such as asolid-state drive (SSD), a magnetic tape drive, optical media drives,HDD/SSD hybrid drives, and other storage systems that write data tostorage media (e.g., magnetic or optical storage media). Alternately oradditionally, the computing device 102 may include an array of mediadrives or serve as a media drive aggregation device or host for multiplemedia drives in which aspects of pulse-based writing may be implemented.

In this example, the disk drive 118 includes a head-disk assembly 124(HDA 124) and drive control module 126 to implement or enablefunctionalities of the hard-disk drive 118. In some cases, the drivecontrol module 126 is implemented as a printed circuit board assembly(PCBA) with semiconductor devices, logic, or other circuitry. The HDA124 includes one or more media disks 128 mounted on an integratedspindle and motor assembly 130. The spindle and motor assembly 130 mayrotate the media disk 128 under (or over) read/write heads 132 coupledwith a head assembly (not shown) of the HDA 124. The media disks 128 maybe coated with a magnetically hard material (e.g., a particulate surfaceor a thin-film surface) and may be written to, or read from, a singleside or both sides.

The read/write heads 132 may be operably coupled with apre-amplifier/writer module 134 (pre-amp/writer 134) of the HDA 124 thatincludes pre-amplifier circuitry and an instance of pulse-based writingcircuitry 136. The pre-amp/writer 134 may receive or store headselection, amplification, or sense current values useful for writingdata to, or reading data from, the magnetic media 202. The pulse-basedwriting circuitry 136 may be configured to function in concert orcoordination with other components of the hard-disk-drive 118 toimplement aspects of pulse-based writing. How the pulse-based writingcircuitry 136 is implemented and used varies and is described throughoutthis disclosure.

As shown in FIG. 1, the example drive control module 126 of thehard-disk drive 118 may include a storage media controller 138, a servocontrol unit 140, and a read/write channel 142 (R/W channel 142). Insome aspects, the read/write channel 142 includes a pulse-based writer144 to generate, manage, or alter various signals or data (e.g., encodedbit stream) to implement features of pulse-based writing for magneticstorage media. How the pulse-based writer 144 is implemented and usedvaries and is described throughout this disclosure. Generally, the drivecontrol module 126 may direct or use the servo control unit 140 tocontrol mechanical operations, such as read/write head 132 positioningthrough the HDA 124 and rotational speed control through the spindle andmotor assembly 130. The drive control module 126 or components thereofmay be implemented as one or more IC chips, a System-on-Chip, aSystem-in-Package, or a microprocessor provided with or implementing ahard-disk-drive controller. The drive control module 126 may alsoinclude drive electronics (not shown) and/or include various interfaces,such as a host-bus interface, storage media interface, spindleinterface, or a pre-amp/writer interface.

By way of example, consider FIG. 2 which provides an exampleconfiguration of the hard-disk drive 118, illustrated generally at 200.As shown in FIG. 2, the HDA 124 of the hard-disk drive 118 includes anintegrated spindle and motor assembly 130 by which media disks 128 ofmagnetic media 202 are supported and/or operated. An arm 204 maymaneuver, and thus position a read/write head 132 (or multipleread/write heads 132) over a desired track 206 of the magnetic media 202on the media disk 128. In various aspects, the read/write head 132 mayinclude various numbers of head elements with combined or separatefunctions (e.g., dedicated R/W functions). For example, the read/writehead 132 may include one or more readers (read heads/elements) and onewriter (write head/element). In other cases, the read/write head 132 mayinclude a dedicated write head (element) and one or more separate,additional dedicated read heads (elements). Alternately or additionally,although multiple arms 204 are shown in FIG. 2, the HDA 124 or spindleand motor assembly may be implemented with a single arm 204 or othersuitable structures for positing the read/write head 132. The HDA 124and the drive control module 126 may be implemented separately, onseparate substrates, and/or as separate PCBAs of a media drive. Signalsor data communicated between the HDA 124 and the drive control module126 may be carried through a flexible printed cable or other suitableconnective structures, such as traces, connectors, bond wires, solderballs, or the like.

FIG. 2 also includes an illustration of example magnets 208 written tothe magnetic media 202 of a media disk 128. One or more of theread/write heads 132 may write magnets to respective ones of the tracks206 of a media disk 128, where sectors are provided for each of thetracks (e.g., a sector of tracks 206). For illustrative purposes, a topmedia disk 128 is shown to include tracks 206, for example, after beingwritten with magnets 208 by a read/write head 132. Generally, duringwrite operations, the read/write head 132 may be driven by a writecurrent provided by the pre-amp/writer 134, whereby an electrical signalis used to generate and/or transfer magnetic fields having associatedpolarities to the media disk 128. In response to application of themagnetic fields or write fields, the read/write head 132 may form aplurality of magnets 208 in magnetic grains of the tracks 206 of themedia disk 128. The HDA 124 of the hard-disk drive 118 may be configuredto perform write operations in accordance with any suitable recordingtechnology, such as perpendicular magnetic recording (PMR), shingledmagnetic recording (SMR), heat-assisted magnetic recording (HAMR),microwave assisted magnetic recording (MAMR), or the like.

As shown at 210, a write head 132 (or read/write head 132 when combined)may write, generate, or polarize one or more magnets in the magneticmedia 202 under the write head 132. With respect to write head geometry,assume that the write head 132 is approximately as long, eitherphysically or equivalently through an effective magnetic field, as 6magnets or 6T (magnet periods or magnetic write periods). In thisexample and in accordance with aspects of pulse-based writing, thepre-amp/writer 134 writes a magnet 212 with a first polarity (shaded),which may correspond to a first bit encoding (e.g., negative transition,encoding a “0”, or zero (0) value). To write the magnet 212, thepre-amp/writer 134 provides a first pulse of write current having afirst polarity to the write head 132 to generate a first magnetic field214 to generate or form the magnet 212. Note that the first magneticfield 214 writes, based on the first pulse of write current, not onlymagnet 212 but the following five magnets 216 with the same polarity.

As shown during the next bit writing period (T+1), the pre-amp/writer134 writes a magnet 218 with a second polarity (non-shaded), which maycorrespond to a second bit encoding (e.g., positive transition, encodinga “1”, or one (1) value). To write magnet 218, the pre-amp/writer 134provides a second pulse of write current having a second polarity to thewrite head 132 to generate a second magnetic field 220 to generate orform the magnet 218. Here, note that the second magnetic field 220writes, based on the second pulse of write current, not only magnet 218but the following five magnets 222 with the same polarity. In otherwords, in aspects of pulse-based writing, once the first bit is writtenat the trailing edge of the write head 132, the write head has alreadywritten six bits (6T) of magnet or a longer magnet on the magnetic mediaunder the write head. As such, a single pulse of write current is oftensufficient to generate magnets of four to six bits (4T-6T) length andless. Thus, a single pulse of current or write field is sufficient towrite 4T and shorter magnets, with additional pulses enabling thewriting of longer magnets. In aspects of pulse-based writing, providinga pulse of current or write field every 4T or 6T may enable the writingof longer magnets, such as for long strings of ones or zeroes moreefficiently or with less distortion to data of neighboring tracks.

FIG. 3 illustrates example configurations of a read/write channel andpre-amplifier generally at 300, which are implemented in accordance withone or more aspects of pulse-based writing for magnetic storage media.In this example, the pulse-based writer 144 is operably coupled with theread/write channel 142 and the pulse-based writing circuitry 136 isoperably coupled with the pre-amp/writer 134 (pre-amp 134). Althoughshown in FIG. 3 as separate components or circuitry, the pulse-basedwriter 144 and pulse-based writing circuitry 136 may be integrated asone component, separated among other components of the hard-disk drive118, and/or integrated with other microelectronics or circuitry of thepre-amp 134 and/or the read/write channel 142.

In this example, a host interface 302 provides write data 304 or otherinformation to the read/write channel 142 or a storage media controlleron which the read/write channel 142 is embodied. Generally, theread/write channel 142 provides, to the pre-amp 134 of a media drive,pre-amp data 306, which may include a signal corresponding to a datapattern intended for writing on the media. In aspects of pulse-basedwriting, the pulse-based writer 144 may alter the pre-amp data 306 sentto the pre-amp 134, such as by inserting transitions, altering bitpolarities, inserting fake bits, or any combination of the like. Thepulse-based writer 144 may also generate or cause the read/write channelto generate a control signal 308 for the pre-amp 134. In some cases, thepulse-based writer 144 may generate a control signal 308 to masktransitions, inhibit or prevent pulsing by the pre-amp 134, or tocontrol or provide an indication of polarity or a state of polaritymodification (e.g., for pre-amp data 306 signals).

For example, in some aspects of pulse-based writing, pulsing away fromtransitions in a data pattern may be facilitated by the pulse-basedwriter 144 injecting two transitions in signaling (pre-amp data 306)provided by the read/write channel 142 to the pre-amp 134, with anadditional control signal (control signal 308) to indicate to thepre-amp 134 to inhibit or prevent pulsing when the control signal isactive (e.g., high). In other words, if the control signal is high, thepre-amp 134 does not generate a write pulse, which enables thegeneration of multiple (e.g., periodic and/or of same polarity) pulsesfor long magnets. For example, for a first transition, the pulse-basedwriter 144 may assert the control signal 308 high and deassert thecontrol signal low for the second transition to provide or generate apulse of a same polarity of a preceding pulse (e.g., a pulse at a startof the magnet) at the second transition.

Generally, the pre-amp 134 or pre-amp circuitry 310 generates orprovides a write current to the write head 132 of the media drive withthe pattern of polarity or transitions corresponding to the pre-amp data306 (modified or not) and/or control signal 308 for pulse-based writing.Based on the data and/or control signals pattern provided by theread/write channel 142 and pulse-based writer 144, the pre-amp 134 maygenerate pulses, or change polarity of, the write current that is sentto the write head 132. As described herein, the pre-amp 134 may alsoprovide an overshoot current at, or proximate, polarity changes toquicken a change of magnetic field of the write head. Alternately oradditionally, the pre-amp circuitry 310 may also implement other writecontrols, such as an overshoot level adjustment, overshoot duration,write-current baseline level, rise/fall speeds for pulse-writingtransitions, or the like.

The write current generated by the pre-amp 134, or a pulse-based writecurrent 312 as shown in FIG. 3, may be provided to a corresponding writehead 132 for the magnetic media 202. Based on the pulse-based current312, the write head 132 may generate a pulsed magnet writing field 314to form magnets that correspond to the pre-amp data 306 or any suitableform of signaling or encoding for data received from the host interface302. For example, the pulsed magnet writing field 314 pulse ontransitions of pre-amp data bits to write or form respective magnets ofcorresponding polarity in the magnetic media 202. In various aspects,the pre-amp 134 may cause or generate the pulsed magnet writing field314 to write long magnets with multiple pulses that form or polarizerespective sections (e.g., multiple bits) of a long magnets, such as 4Tor 5T sections.

In some aspects, the pulse-based writer 144 may also implement writecurrent relaxation, which may turn off or set write current to apre-bias state (non-I_(w) state). In some cases, the pulse-based writer144 turns off the write current or magnetic field (write field) towardsor proximate to an end of a long magnet written (e.g., consecutive bitswritten with a same polarity) to the magnetic storage media. By sodoing, the read/write channel 142 and/or pre-amp 134 may be prepared(e.g., avoiding a full positive to negative write current swing) for atransition of the write current or pulse to opposite polarity, thusproviding a faster or cleaner transition on a next magnet. For example,the pulse-based writer 144 may cause the pre-amp 134 or pulse-basedwriting circuitry 136 to provide relaxed write current 316 and/orpulse-based write current 312 to the write head 132 in accordance withvarious aspects described herein. In some cases, a benefit of writecurrent relaxation or pulse-based writing implemented by the pulse-basedwriter 144 may include that the magnetic field is not applied when themagnetic field is not needed (e.g., for long magnets), and this may inturn reduce an effect the magnetic field has on previously written dataon neighboring data tracks, such as reduced degradation or distortion.

Techniques of Pulse-Based Writing for Magnetic Storage Media

The following discussion describes techniques of pulse-based writing formagnetic storage media, which may improve writing efficiency or reducedistortion of previously written data in neighboring tracks. Thesetechniques may be implemented using any of the environments and entitiesdescribed herein, such as the pre-amp/writer 134, pulse-based writingcircuitry 136, read/write channel 142, or pulse-based writer 144. Thesetechniques include methods illustrated in FIGS. 4, 7, 9, 11, and 13,each of which is shown as a set of operations performed by one or moreentities.

These methods are not necessarily limited to the orders of operationsshown in the associated figures. Rather, any of the operations may berepeated, skipped, substituted, or re-ordered to implement variousaspects described herein. Further, these methods may be used inconjunction with one another, in whole or in part, whether performed bythe same entity, separate entities, or any combination thereof. Forexample, aspects of the methods described may be combined to implementpulse-based writing for magnetic media with a combination of injectedtransitions, transition masking, polarity control, modified pre-ampdata, and/or write current relaxation. In portions of the followingdiscussion, reference will be made to the operating environment 100 ofFIG. 1, entities of FIG. 2 and/or FIG. 3. Such reference is not to betaken as limiting described aspects to the operating environment 100,entities, configurations, or implementations, but rather as illustrativeof one of a variety of examples. Alternately or additionally, operationsof the methods may also be implemented by or with entities describedwith reference to the System-on-Chip of FIG. 15 and/or the storage mediacontroller of FIG. 16.

FIG. 4 depicts an example method 400 for implementing pulse-basedwriting of magnetic storage media, including operations performed by orwith the pulse-based writing circuitry 136, read/write channel 142,and/or pulse-based writer 144.

At 402, a pulse-based writer determines that a string of data bitshaving a same polarity corresponds to a magnet longer than a thresholdassociated with a magnetic media writer. The threshold may correspondwith or be based on a geometry of a write head of the magnetic mediawriter, such as approximately a length of the write head or one or morebits shorter (e.g., 4T for a 5T long write head). In some cases, anumber of consecutive bits of the same polarity are compared with apredefined threshold. As described herein, the predefined threshold maybe defined based on the geometry of the write head or the geometry ofmagnets that are written to the magnetic storage media. In such cases,the predefined threshold may correspond to an approximate length or aneffective length of the write head with respect to a length of themagnets. For example, the predefined threshold may be set to enabledeterminations or detections of magnets that meet or exceed four to sixbit periods or magnet periods (e.g., 4T, 5T, or 6T).

At 404, the pulse-based writer inserts, into the string of data bits, atleast one transition to a polarity opposite to the polarity of thestring of data bits. In some cases, the pulse-based writer inserts pairsof fake transitions or bits that are effective to cause the magneticmedia writer to generate pulses of write current. In some cases, a firsttransition and a second transition are inserted into the string of databits or a signal representing or encoding the string of data bits, suchas a non-return-to-zero (NRZ) encoded data signal or into a pre-amp datawaveform. A polarity of the first transition is opposite to the polarityof the second transition. For example, a pair of transitions may beinserted into the string of bits as a 1T or 2T bit having an oppositepolarity. Alternately or additionally, the first transition and thesecond transition may be consecutive transitions in the signal of thedata bits that are inserted with approximately one bit, two bits, onemagnet period (1T), or two magnet periods (2T) of separation.

Optionally at 406, the pulse-based writer asserts a control signal tothe magnetic media writer. Alternately or additionally, the pulse-basedwriter may deassert or change a state of the control signal or a controlline to cause the magnetic media writer (e.g., pulse-based writingcircuitry of the writer) to act in accordance with aspects ofpulse-based writing or to provide an indication to the magnetic mediawriter. In some cases, a control signal (or other logical indication) tothe magnetic media writer may be effective to mask at least onetransition inserted into the data bits or data signal. In other cases,the control signal may indicate, to the magnetic media writer, apolarity of the string of data bits that corresponds to the magnet or apolarity of a subsequent string of data bits. In such cases, the controlsignal may cause the magnetic media writer to pulse the write currentprovided to the write head in a polarity opposite to the polarity of atransition inserted into the string of data bits.

At 408, the pulse-based writer transmits, to the magnetic media writer,the string of data bits including the transition causing the write headto pulse while writing the magnet to the magnetic media. In someaspects, one of the transitions or the control signal may cause themagnetic media writer to generate or provide a pulse of write current tothe write head. One or more pulses of write current, provided after aninitial pulse at a start of a magnet, may enable the pulse-based writerto write long magnets more efficiently or with minimal distortion ofdata in neighboring tracks (e.g., to the track being written withpulse-based writing).

Optionally at 410, the pulse-based writer deasserts the control signalto the magnetic media writer. In some cases, the control signal may bedeasserted proximate to an end of a long magnet to allow write currentto relax or settle before a next transition or to pulse toward anopposite polarity. For example, the pulse-based writer may determinethat at least a portion of subsequent data bits have the same polarityand correspond to another magnet longer than the write head of themagnetic media writer. In response to an upcoming transition or anotherlong magnet, the control signal may be deasserted. From operation 410,the method 400 may return to operation 402 to implement anotheriteration of method 400, or to any other operation implementing aspectsof pulse-based writing, such as providing multiple pulses during a longmagnet.

By way of example, consider FIG. 5 which illustrates at 500 an examplegraph of pre-amp data that includes transitions in accordance withvarious aspects of pulse-based writing. The graphs or waveforms of FIG.5 include NRZ data 502, pre-amp data 504, a control signal 506, andwrite current 508. Generally, the NRZ data 502 may be provided to orencoded by a read/write channel 142. In some aspects, a pulse-basedwriter 144 alters or modifies the NRZ data 502 to provide the pre-ampdata 504 for a pre-amp/writer 134 or pre-amplifier circuitry 310.Alternately or additionally, the pulse-based writer 144 may generate orset the control signal 506 to the pre-amp/writer 134 or pre-amplifiercircuitry 310 (or pulse-based writing circuitry 136). In variousaspects, based on the pre-amp data 504 and/or control signal 506, thepre-amp/writer 134 or pre-amplifier circuitry 310 generates pulses ofwrite current 508 to form or write magnets to magnetic storage media.

In some aspects, the NRZ data 502 (or NRZ signal) may represent asequence of digital bits, or a data pattern, to be encoded on themagnetic storage or recording medium. Alternately or additionally, theNRZ data may be implemented as non-return-to-zero inverted (NRZi) forencoding data bits and may be based on a read/write channelconfiguration or the polarity of pre-amp circuitry. With reference tothe graphs depicted in this and other figures (e.g., FIG. 6, 8, 10, or12), the NRZ data may be shown as a binary signal having a rectangularpulse-amplitude modulation with levels associated with negative (−) andpositive (+) polarities. Generally, transitions to an alternate level(or an absence of a transition) of the NRZ data 502 during a window orbit period may represent an individual coded bit. As shown in FIG. 5,the NRZ data 502 has an amplitude that alternates between a high level(+ polarity) and a low level (− polarity). Moreover, the NRZ data 502has multiple transitions, as the signal rises or falls to reach analternate polarity level. As an example, the NRZ data 502 may representa “1” at rising edges, where the signal transitions from a low to a highlevel. Additionally, the NRZ data 502 may represent a “0” at fallingedges, where the signal drops from the high level to the lower level,examples of which are provided in FIG. 5 and other figures forconvenient reference.

The NRZ data 502 may be provided to or generated by the read/writechannel 142, which in turn provides the pre-amp data 504 to the pre-amp134. In some aspects, the read/write channel 142 or the pulse-basedwriter 144 alters or modifies the NRZ data 502 to provide the pre-ampdata 504 to enable pulse-based writing for the magnetic storage media.Based on the pre-amp data 504, control signal 506, and/or other varioussettings, the pre-amp 134 generates or controls the write current 508.As shown in FIG. 5, the write current 508 may include multiplestep-waves that generally begin with an overshoot at a polar transition(e.g., edge of the NRZ data 502). The overshoot amplitude (OSA) may bedescribed as a substantially increased (or spike) level for the writecurrent 508. By starting with an increased current, as produced by theovershoot amplitude, the pre-amp/writer 134 may change the polarities ofthe magnetic fields faster, thereby ensuring that the writer is set tothe proper state needed for a sharp transition in the encoded data.After the initial overshoot, the amplitude of the write current 508 maysettle to a more stable baseline current level for the remainder of themagnet writing duration. As such, an increased overshoot amplitude mayenable the pre-amp/writer 134 to compensate for writing higher frequencydata patterns with a lower speed write head.

As shown in FIG. 5, the write current 508 amplitude may be selectivelyset to at least five levels. The write current 508 graph includes a zerolevel or off state, a write current baseline (I_(w)), a write currentwith overshoot amplitude (I_(w)+OSA), a negative write current baseline(−I_(w)), and a negative write current with overshoot amplitude(−I_(w)+OSA). Alternately or additionally, the pre-amp/writer 134 may beconfigurable to provide a pre-bias level that is slightly positive ornegative for aiding in transitions of the write current 508. Forexample, in some aspects of pulse-based writing or current relaxation,the pre-amp/writer 134 may transition from a positive write current to anegative pre-bias state in anticipation of a negative pulse of the writecurrent (or vice versa).

Generally, the pulse-based writer 144, read/write channel 142, and/orthe pre-amp/writer 134 may determine or select an amplitude of the writecurrent 508. For example, the pulse-based writer 144 may select anovershoot amplitude for pulsing the write current on a transition, abaseline write current while writing another section of a magnet (e.g.,intermediate section of a long magnet), and an off-state or pre-biascondition for the write current before the next transition or pulse to adifferent polarity (e.g., for write current relaxation at a tail end ofa long magnet). How the pulse-based writer 144 implements write currentpulses or control varies and is described throughout the disclosure.

In this example, the pulse-based writer 144 of the read/write channel142 may be configured to insert pairs of fake transitions into an NRZ orNRZi data path for various magnets or magnets that exceed a geometry ofa write head, such as 5T or longer magnets. The pulse-based writer isalso configured to use the control signal 506 to inhibit or preventpulses on a first or leading transition of the pair of transitions. Asshown in FIG. 5, the pulse-based writer 144 may insert a pair of faketransitions 510 and 512 to modify or alter the pre-amp data 504. Inother words, a 5T magnet (0111110) may be modified as or to mimic a1T1T3T magnet in the pre-amp data 504.

In some cases, the pulse-based writer 144 also asserts or generates acontrol signal at 514 to mask the leading fake transition 510 causingthe write current 508 to pulse at 516 with the same direction as theprevious pulse at the start of the magnet. In other words, when thecontrol signal 506 is high or asserted, the pre-amp/writer 134 orpulse-writing circuitry 136 may be inhibited or prevented fromoutputting a pulse of write current. The pulse-based writer 144 may alsoinsert fake transitions in the NRZ data 502 that correspond torespective long magnets as shown at 518, 520, and/or 522. As shown inFIG. 5, the pulse-based writer 144 also asserts the control signal 506at 524, 526, and 528 to prevent the pre-amp/writer 134 from pulsing onthe leading fake transition to provide the pulses of write current shownat 530, 532, and 534.

The read/write channel 142 or the pulse-based writer 144 may beimplemented through any suitable combination of logic, circuitry, orsoftware executed by a hardware-based processor to implement aspects ofpulse-based writing. In some cases, aspects of method 400 and/or signalwaveforms of FIG. 5 may be implemented through the logic of Table 1 inwhich:

TABLE 1 Logic for transitions on an NRZi path for pre-amp dataPulse_3T_EN Control Signal 0 w_(i) = !(w_(i−2)|w_(i−1)|v_(i−1)|v_(i)|v_(i+1)|v_(i+2))&(v_(i+3) |!(v_(i−2)|w_(i−3))) 1 w_(i) = ! (w_(i−1)|v_(i)|v_(i+1)|v_(i+2))&(v_(i+3)|! (v_(i−1)|w_(i−2))) v_(i) denotes NRZi bit at time i v′_(i) denotesNRZi sequence sent to preamp (v′_(i) = v_(i) + w_(i) + w_(i−1), +denotes XOR) w_(i) denotes Control signal at time i

By pulsing the write current 508 as shown in FIG. 5, the pulse-basedwriter 144 may enable the formation of magnets in magnetic media moreefficiently or with less distortion to the data in neighboring tracks.

FIG. 6 illustrates another example graph of pre-amp data at 600 thatincludes transitions in accordance with various aspects of pulse-basedwriting. The graphs or waveforms of FIG. 6 include NRZ data 602, pre-ampdata 604, a control signal 606, and write current 608. Generally, theNRZ data 602 may be provided to or encoded by the read/write channel142. In some aspects, a pulse-based writer 144 alters or modifies theNRZ data 602 to provide the pre-amp data 604 for a pre-amp/writer 134 orpre-amplifier circuitry 310. Alternately or additionally, thepulse-based writer 144 may generate or set the control signal 606 to thepre-amp/writer 134 or pre-amplifier circuitry 310 (or pulse-basedwriting circuitry 136). In various aspects, based on the pre-amp data604 and/or the control signal 606, the pre-amp/writer 134 orpre-amplifier circuitry 310 generates pulses of write current 608 toform or write magnets to magnetic storage media. Any or all of the NRZdata 602, pre-amp data 604, control signal 606, and/or write current 608may be configured or implemented similarly as described with referenceto FIG. 5 or other aspects of pulse-based writing.

In this example, the pulse-based writer 144 of the read/write channel142 may be configured to insert pairs of fake transitions (e.g., 2Tinverted signals) into an NRZ or NRZi data path for various magnets ormagnets that exceed a geometry of a write head, such as 5T or longermagnets. The pulse-based writer is also configured to use the controlsignal 606 to inhibit or prevent pulses on a first or leading transitionof the pair of transitions. As shown in FIG. 6, the pulse-based writer144 may insert a pair of fake transitions 610 and 612 to modify or alterthe pre-amp data 604. In other words, a 5T magnet (0111110) may bemodified as or to mimic a 2T2T1T magnet (0110010) in the pre-amp data604.

In some cases, the pulse-based writer 144 also asserts or generates acontrol signal at 614 to mask the leading fake transition 610 causingthe write current 608 to pulse at 616 with the same direction as theprevious pulse at the start of the magnet. In other words, when thecontrol signal 606 is high or asserted, the pre-amp/writer 134 orpulse-writing circuitry 136 may be inhibited or prevented fromoutputting a pulse of write current. The pulse-based writer 144 may alsoinsert fake transitions in the NRZ data 602 that correspond torespective long magnets as shown at 618, 620, and/or 622. As shown inFIG. 6, the pulse-based writer 144 also asserts the control signal 606at 624, 626, and 628 to prevent the pre-amp/writer 134 from pulsing onthe leading fake transition effective to provide pulses of write currentshown at 630, 632, and 634.

The read/write channel 142 or pulse-based writer 144 may be implementedthrough any suitable combination of logic, circuitry, or softwareexecuted by a hardware-based processor to implement aspects ofpulse-based writing. In some cases, aspects of method 400 and/or signalwaveforms of FIG. 6 may be implemented through the logic of Table 2 inwhich:

TABLE 2 Logic for 2T transitions on an NRZi path for pre-amp dataControl Signal w_(i) = ! (w_(i−1)|v_(i)|v_(i+1)|v_(i+2))&(v_(i+3) |!(v_(i−1)|w_(i−2))) v_(i) denotes NRZi bit at time i v′_(i) denotes NRZisequence sent to preamp (v′_(i) = v_(i) + w_(i) + w_(i−1), + denotesXOR) w_(i) denotes control signal at time i u_(i) denotes NRZ bit attime i (u_(i) = u_(i−1) + v_(i)) u′_(i) denotes NRZ sequence sent topreamp (u′_(i) = u′_(i−1) + v′_(i))

By pulsing the write current 608 as shown in FIG. 6, the pulse-basedwriter 144 may enable the formation of magnets in magnetic media moreefficiently or with less distortion to the data in neighboring tracks.

FIG. 7 depicts an example method 700 for pulse-based writing withpolarity control. The operations of method 700 may be performed by orwith the pulse-based writing circuitry 136, read/write channel 142,and/or pulse-based writer 144.

At 702, a pulse-based writer determines that a string of data bitshaving the same polarity corresponds to a threshold associated with amagnetic media writer. The threshold may correspond with or be based ona geometry of a write head of the magnetic media writer, such asapproximately a length of the write head or one or more bits shorter(e.g., 4T for a 5T long write head). In some cases, a number ofconsecutive bits of the same polarity are compared with a predefinedthreshold. As described herein, the predefined threshold may be definedbased on the geometry of the write head or the geometry of magnets thatare written to the magnetic storage media. In such cases, the predefinedthreshold may correspond to an approximate length or effective length ofthe write head with respect to the length of the magnets. For example,the predefined threshold may be set to enable determination or detectionof magnets that meet or exceed four to six bit periods or magnet periods(e.g., 4T, 5T, or 6T).

At 704, the pulse-based writer asserts, in response to thedetermination, a signal to the magnetic media writer indicative of thepolarity state of the data signal to which the magnet corresponds. Insome cases, the control signal asserted to the magnetic media writer(e.g., pre-amp/writer 134 and/or write head 132) enables polaritycontrol or management of the magnetic media writer. For example, the useof the control signal for polarity control may enable the pulse-basedwriter to alter the polarity of the magnetic media writer before a faketransition in encoded data bits is processed. Alternately oradditionally, the control signal may change polarity for or with eachfake transition that is injected into an encoded data bit signal.

At 706, the pulse-based writer inserts a transition into the data signalbased on a previous transition of the data signal and the indicatedpolarity state. For example, if the control signal is in the same state,then a transition with the opposite polarity may be inserted.Alternately, if the control signal has changed since the lasttransition, a fake transition may be injected with the same polarity asa previous or preceding transition. In some cases, the pulse-basedwriter may insert a fake transition every 4T of a long magnet with anoption for every 3T. In other cases, an option may enable the insertionof fake transitions at 1T in the event the next bit or sample is anothertransition of the bit pattern. Alternately or additionally, for multiple1T transitions, shorter pulses (e.g., less than 1T) may be implemented,or another control signal may be provided to the pre-amp to indicatewhether it is pulsing on a rising edge or a falling edge of the NRZidata signal.

At 708, the pulse-based writer transmits, to the magnetic media writerand while the signal is asserted, the data signal including thetransition to cause the write head to pulse while writing the magnet. Insome aspects, one of the transitions in combination with the polaritycontrol signal may cause the magnetic media writer to generate orprovide a pulse of the write current to the write head. One or morepulses of write current, provided after an initial pulse at a start of amagnet, may enable the pulse-based writer to write long magnets moreefficiently or with minimal distortion of data in neighboring tracks.From operation 708, the method 700 may return to operation 702 toimplement another iteration of the method 700, or to any other operationto implement aspects of pulse-based writing, such as to provide multiplepulses during a long magnet.

By way of example, consider FIG. 8 which illustrates example graphs ofpre-amp data and a control signal for polarity control in accordancewith one or more aspects. The graphs or waveforms of FIG. 8 include NRZdata 802, pre-amp data 804, a control signal 806, and write current 808.Generally, the NRZ data 802 (or NRZi data) may be provided to or encodedby a read/write channel 142. In some aspects, a pulse-based writer 144alters or modifies (e.g., inverts) the NRZ data 802 to provide thepre-amp data 804 for a pre-amp/writer 134 or pre-amplifier circuitry310. Alternately or additionally, the pulse-based writer 144 maygenerate or set the control signal 806 to the pre-amp/writer 134 orpre-amplifier circuitry 310 (or pulse-based writing circuitry 136). Invarious aspects, based on the pre-amp data 804 and/or control signal806, the pre-amp/writer 134 or pre-amplifier circuitry 310 generatespulses of write current 808 to form or write magnets to magnetic storagemedia. Any or all of the NRZ data 802, pre-amp data 804, control signal806, and/or write current 808 may be configured or implemented similarlyto that described with reference to FIG. 5 or other aspects ofpulse-based writing.

In this example, the pulse-based writer 144 of the read/write channel142 may be configured to insert a fake transition every 4T of a longmagnet with an option for every 3T, for magnets that exceed a geometryof a write head. The pulse-based writer is also configured to use thecontrol signal 806 to indicate or control polarity at the pre-amp/writer134. As shown in FIG. 8, the pulse-based writer 144 may assert thecontrol signal at 810 to change polarity before a fake transition 812occurs and the NRZ data is inverted at 814. As shown in FIG. 8, the faketransition 812 is effective to provide a pulse of write current at 816with the same polarity as the previous transition. At 818, thepulse-based writer 144 again changes polarity before another faketransition at 820 to provide another pulse of the write current at 822.Here, note that the NRZ data polarity is reversed again whereby thepre-amp data 804 has the same polarity at 824. Concluding the presentexample, the pulse-based writer 144 changes polarity once more at 826 toenable another fake transition 828, which generates a pulse of the writecurrent at 830.

The read/write channel 142 or the pulse-based writer 144 may beimplemented through any suitable combination of logic, circuitry, orsoftware executed by a hardware-based processor to implement aspects ofpulse-based writing. In some cases, aspects of method 700 and/or signalwaveforms of FIG. 8 may be implemented through the logic of Table 3 inwhich:

TABLE 3 Logic for pulse writing with polarity control Pulse_3T_ENPulse_GAP_DIS Control Signal 0 0 p_(i) = !(p_(i−2)|p_(i−1)|v_(i−2)|v_(i−1)|v_(i))&(v_(i+1)|! (p_(i−3)|v_(i−3))) 01 p_(i) = ! (p_(i−3)|p_(i−2)|p_(i−1)|v_(i−3)|v_(i−2)|v_(i−1)|v_(i)) 1 0p_(i) = ! (p_(i−1)|v_(i−1)|v_(i))&(v_(i+1)|! (p_(i−2)|v_(i−2))) 1 1p_(i) = ! (p_(i−2)|p_(i−1)|v_(i−2)|v_(i−1)|v_(i)) Let v_(i) denote NRZbit transition, let v′_(i) denote transition sequence sent to thepre-amp, and let p_(i) denote control signal polarity switch Let trepresent value of PULSE_3T_EN: One-bit register to enable pulsing every3T instead of every 4T Let G represent PULSE_GAP_DIS[0] One-bit registerto disable pulsing 1T early in case of upcoming transitions A controlsignal will transition based on p_(i) in table below when PULSE_EN = 1v_(i) denotes NRZi bit at time i v′_(i) denotes NRZi sequence sent topreamp (v′_(i) = v′_(i) + p_(i) + denotes XOR) p_(i) denotes polarityswitch signal at time i (w_(i) = w_(i−1) + p_(i), + denotes XOR)

By pulsing the write current 808 as shown in FIG. 8, the pulse-basedwriter 144 may enable the formation of magnets in magnetic media moreefficiently or with less distortion to data in neighboring tracks.

FIG. 9 depicts an example method 900 for pulse-based writing based on acontrol signal. The operations of method 900 may be performed by or withthe pulse-based writing circuitry 136, read/write channel 142, and/orpulse-based writer 144.

At 902, a pulse-based writer determines that a string of data bitshaving a same polarity corresponds to a threshold associated with amagnetic media writer. The threshold may correspond with or be based ona geometry of a write head of the magnetic media writer, such asapproximately a length of the write head or one or more bits shorter(e.g., 4T for a 5T long write head). In some cases, a number ofconsecutive bits of the same polarity are compared with a predefinedthreshold. As described herein, the predefined threshold may be definedbased on the geometry of the write head or the geometry of magnets thatare written to the magnetic storage media.

At 904, the pulse-based writer generates, in response to thedetermination, a signal useful to provide a pulse of write current. Insome aspects, the pulse-based writer pulses the control signal at 4T orsimilar intervals for long magnets. The pulse-based writer may beconfigured to pulse earlier for a last pulse so that the last pulseoccurs at least 2-3T prior to a next transition to a different polarity.Alternately or additionally, the pre-amp/writer may be configured totrack the polarity, such as to ensure that the control signal causesadditional pulses of the previous or same transition of a magnet beingwritten.

At 906, the pulse-based writer pulses, via the magnetic media writer,the write current based on the signal and the polarity of a previouspulse of the write current. Generally, the control signal may be used toindicate when an additional or extra pulse is needed to write anotherportion of a long magnet. In response to the control signal, thepre-amp/writer may pulse the write current based on the control signaland the polarity of a previous transition of the encoded data togenerate the extra pulses. From operation 906, the method 900 may returnto operation 902 to implement another iteration of the method 900, or toany other operation (906) to implement aspects of pulse-based writing,such as to provide multiple pulses for a long magnet.

By way of example, consider FIG. 10 which illustrates at 1000 an examplegraph of a control signal for pulse-based writing in accordance withvarious aspects of pulse-based writing. The graphs or waveforms of FIG.10 include NRZ data 1002, a control signal 1004, and a write current1006. Generally, the NRZ data 1002 (or NRZi data) may be provided to orencoded by a read/write channel 142. In some aspects, a pulse-basedwriter 144 may generate or set the control signal 1004 to thepre-amp/writer 134 or the pre-amplifier circuitry 310 (or pulse-basedwriting circuitry 136) to cause or trigger pulses of write current. Anyor all of the NRZ data 1002, control signal 1004, and/or write current1006 may be configured or implemented similarly as described withreference to FIG. 5 or other aspects of pulse-based writing.

In this example, the pulse-based writer 144 of the read/write channel142 may be configured to use the control signal 1004 to pulse the writecurrent 1006 at 4T intervals for magnets that exceed a geometry of awrite head. As shown in FIG. 10, for data that corresponds to respectivelong magnets, the pulse-based writer 144 may assert the control signal1004 at 1008, 1010, 1012, and/or 1014 to cause or trigger pulses in thewrite current 1006. Concluding the present example and in accordancewith the control signal 1004 provided by the pulse-based writer, thepre-amp/writer generates pulses of the write current 1006 at 1016, 1018,1020, and 1022.

FIG. 11 depicts an example method 1100 for relaxing the write current ofa magnetic media writer. The operations of method 1100 may be performedby or with the pulse-based writing circuitry 136, read/write channel142, and/or pulse-based writer 144.

At 1102, a pulse-based writer determines that a string of data bitshaving the same polarity corresponds to a threshold associated with amagnetic media writer (e.g., a length of the write head). The thresholdmay correspond with or be based on a geometry of a write head of themagnetic media writer, such as approximately a length of the write heador one or more bits shorter (e.g., 4T for a 5T long write head). In somecases, a number of consecutive bits of the same polarity are comparedwith a predefined threshold. Alternately or additionally, the predefinedthreshold may be defined based on the geometry of the write head or thegeometry of magnets that are written to the magnetic storage media.

At 1104, the pulse-based writer asserts, in response to thedetermination, a signal useful to extend a pulse of write current for atleast a portion of the magnet. Alternately or additionally, the signalmay be useful to relax the write current from an overshoot amplitude toa baseline write current or to an off-state or pre-bias voltage for atransition to the opposite polarity. In some aspects, the signal, suchas the control signal provided to the pre-amp/writer, is used todirectly control or affect the write current. The control signal may beasserted at a beginning of a long magnet and deasserted at a predefinedduration of time before a transition to a next polarity.

At 1106, the pulse-based writer maintains, via the magnetic mediawriter, at least a portion of the write current based on the signal andthe length of the magnet. For example, based on the asserted controlsignal, the magnetic media writer may relax the write current from anovershoot level to a baseline write level. Alternately or additionally,in response to deassertion of the control signal, the magnetic mediawriter may relax the write current to an off-state (e.g., from apositive level) or a pre-bias state (e.g., less than 0) in advance to atransition to the opposite polarity (e.g., negative polarity).

Optionally at 1108, the pulse-based writer deasserts, based on thelength of the magnet, the signal to enable the write current to ceaseprior to the next pulse transition. As noted, the control signal may bedeasserted based on an upcoming transition to the opposite polarity. Byso doing, an overall swing of write current at the next transition maybe reduced, enabling a faster or cleaner transition by the magneticmedia writer.

By way of example, consider FIG. 12 which illustrates at 1200 an examplegraph of a control signal useful to relax write the current inaccordance with one or more aspects. The graphs or waveforms of FIG. 12include NRZ data 1202, a control signal 1204, and write current 1206.Generally, the NRZ data 1202 (or NRZi data) may be provided to orencoded by a read/write channel 142. In some aspects, the pulse-basedwriter 144 may generate or set the control signal 1204 to thepre-amp/writer 134 or pre-amplifier circuitry 310 (or pulse-basedwriting circuitry 136). In various aspects, based on the control signal1204, the pre-amp/writer 134 or pre-amplifier circuitry 310 relaxes thewrite current 1206, such as when forming or writing long magnets. Any orall of the NRZ data 1202, control signal 1204, and/or write current 1206may be configured or implemented similarly as described with referenceto FIG. 5 or other aspects of pulse-based writing.

In this example, the pulse-based writer 144 of the read/write channel142 may be configured to control the write current directly, such as tosupport two levels of write current or current relaxation. Generally,the pulse-based writer 144 may assert the control signal 1204 at thebeginning of a magnet and deassert the control line 1204 approximately4T prior to a transition of another magnet. In other words, the controlsignal 1204 may pulse for long magnets and relax to a lower writecurrent (of the same polarity), off-state, or pre-bias setting near thetail end of a magnet.

As shown in FIG. 12, the pulse-based writer 144 may assert the controlsignal at 1208 to relax the write current 1006 to a baseline level, andthen deassert the control line at 1210 (˜4T prior to the transition) toallow the write current to settle to about 0 or an off-state. By sodoing, the write current may cleanly or quickly transition based on thepolarity of the next magnet to be written. Similarly, the control signal1204 may also be deasserted at 1216, 1218, and/or 1220 in accordancewith aspects of current relaxation. As shown in FIG. 12, this enablesthe write current to relax at 1222, 1224, and 1226 to a baseline currentwhile at least a portion of a long magnet is written, and then relaxfurther to approximately 0 or an opposite-polarity pre-bias state for anupcoming transition.

The read/write channel 142 or pulse-based writer 144 may be implementedthrough any suitable combination of logic, circuitry, or softwareexecuted by a hardware-based processor to implement aspects ofpulse-based writing. In some cases, aspects of method 1100 and/or signalwaveforms of FIG. 12 may be implemented through the logic of Equations 1and 2 in which:

Control signal goes down 3T prior to next transition:

w _(i)=!(v _(i+3) |v _(i+2) |v _(i+1))

Equation 1: Control Signal for 3T Advance Transitions

Control signal goes down 4T prior to next transition:

w _(i)=!(v _(i+4) |v _(i+3) |v _(i+2) |v _(i+1))

Equation 2: Control Signal for 4T Advance Transitions

With register support provided by:3T_RELAX_EN: One-bit register forcing control signal to operate in relaxmode With 3T_RELAX_EN=1, control signal goes down 3T before nexttransition

FIG. 13 depicts an example method 1300 for relaxing write current withtransitions inserted in pre-amp data. The operations of method 1300 maybe performed by or with the pulse-based writing circuitry 136,read/write channel 142, and/or pulse-based writer 144.

At 1302, a pulse-based writer determines that the length of a magnetmeets or exceeds a predefined threshold associated with a write head ofa magnetic media writer. The predefined threshold may be configuredbased on the geometry of the write head relative to the bit size ofmagnets in the magnetic storage media associated with which the writehead. For example, the predefined threshold may be used to detect ordetermine that the magnet is longer than the write head of a magneticmedia writer and may be a candidate magnet for current relaxation.

At 1304, the pulse-based writer asserts, in response to thedetermination, a signal to the magnetic media writer to prevent pulsingof write current. In some aspects, the signal is a control signal thatmay be used to mask transitions that may be useful to implement currentrelaxation. In other words, when the control signal is asserted, amagnetic media writer (e.g., pre-amp/writer) may not change or output apulse of the write current in response to transitions of the data signalor waveform. Alternately or additionally, the magnetic media writer maybe configured to set the write current to a baseline level, an off-state(0), or an opposite-polarity pre-bias level.

At 1306, the pulse-based writer inserts at least one transition into adata signal to which the magnet corresponds based on the length of themagnet. In some cases, pairs of fake transitions or an inverted signalmay be inserted into the data signal or a data waveform. The transitionsor inverted signal may be inserted at a predefined spacing or durationprior to a next transition, such as 4T or 6T prior to an end of a magnetto which the data corresponds.

At 1308, the pulse-based writer transmits, to the magnetic media writerwhile the signal is asserted, the data signal including the transitioneffective to enable the write current to decrease prior to the nextpulse transition. As noted, the fake transitions may be inserted basedon an upcoming transition to the opposite polarity to allow the writecurrent to relax from an overshoot current to a baseline current, zerocurrent, or opposite-polarity pre-bias current. By so doing, an overallswing of write current at the next transition may be reduced, enabling afaster or cleaner transition by the magnetic media writer.

By way of example, consider FIG. 14 which illustrates at 1400 an examplegraph of pre-amp data that includes transitions in accordance with oneor more aspects of current relaxation. The graphs or waveforms of FIG.14 include NRZ data 1402, pre-amp data 1404, a control signal 1406, andwrite current 1408. Generally, the NRZ data 1402 (or NRZi data) may beprovided to or encoded by a read/write channel 142. In some aspects, apulse-based writer 144 alters or modifies (e.g., inverts) the NRZ data1402 to provide the pre-amp data 1404 for a pre-amp/writer 134 orpre-amplifier circuitry 310. Alternately or additionally, thepulse-based writer 144 may generate or set the control signal 1406 tothe pre-amp/writer 134 or pre-amplifier circuitry 310 (or pulse-basedwriting circuitry 136). In various aspects, based on the pre-amp data1404 and/or control signal 1406, the pre-amp/writer 134 or pre-amplifiercircuitry 310 relax the write current 1408 from an overshoot level (orother initial or max value) to a lower write current, off-state, orpre-bias current. Any or all of the NRZ data 1402, pre-amp data 1404,control signal 1406, and/or write current 1408 may be configured orimplemented similarly as described with reference to FIG. 5 or otheraspects of pulse-based writing.

In this example, the pulse-based writer 144 of the read/write channel142 may be configured to insert pairs of fake transitions or invertedsignals 4T prior to the end of the magnet. In some aspects, this may beeffective to disable or reduce the write current 1408 without generatingadditional pulses in the write current. As such, combined aspects ofpulse-based writing and current relaxation may be implemented withmultiple control signals or registers shared between the read/writechannel and the pre-amp/writer of a media drive. In this example, thepulse-based writer 144 is also configured to use or generate the controlsignal to mask both of the fake transitions, where if control signal ishigh, then the pre-amp/writer does not output a write pulse for thattransition. Instead, the pre-amp/writer may set the write current to 0or another programmable or predefined value. For example, thepulse-based writer may assert the control signal 1406 at 1410 and insertfake transitions at 1412 such that a 5T magnet (0111110) becomes 1T1T3T(0101110) as shown in FIG. 14. Alternately, a pair of fake transitionscould be spaced or separated approximately by 2T, providing a 5T magnetthat becomes 2T2T1T (0110010). As shown in FIG. 14, these transitionsare effective to cause the write current 1408 to relax to the baselinewrite current at 1414 and to zero or an off-state at 1416. Similarly,the pulse-based writer may assert the control line 1406 at 1418, 1420,and/or 1422 to mask pairs of fake transitions inserted at 1424, 1426,and 1428. Responsive to these masked transitions, the pre-amp/writer mayrelax the write current 1408 as shown at 1430, 1432, and 1434. By sodoing, an overall swing of the write current at the next transition maybe reduced, enabling a faster or cleaner transition by the magneticmedia writer.

The read/write channel 142 or pulse-based writer 144 may be implementedthrough any suitable combination of logic, circuitry, or softwareexecuted by a hardware-based processor to implement aspects ofpulse-based writing. In some cases, aspects of method 1300 and/or signalwaveforms of FIG. 14 may be implemented through the logic of Table 4 inwhich:

TABLE 4 Logic for current relaxation with fake bits Relax_3T_ENRelax_Early _EN Control Signal 0 0 p_(i) = !(v_(i+3)|v_(i+2)|v_(i+1)|v_(i))&v_(i+4) 0 1 p_(i) = !(v_(i+1)|v_(i))&[(v_(i+4) &!(v_(i+3)|v_(i+2)))|(v_(i−1)&(v_(i+2)|v_(i+3)))] 1 0 p_(i) = !(v_(i+2)|v_(i+1)|v_(i))&v_(i+3) 1 1 p_(i) = ! (v_(i+1)|v_(i))&[(v_(i+3)&! v_(i+2))|v_(i−1)&v_(i+2))] Control signal will be high based on p_(i)and p_(i−1) in table below v_(i) denotes NRZi bit at time i v′_(i)denotes NRZi sequence sent to preamp (v_(i)′ = v_(i) + p_(i) +p_(i−1), + denotes XOR) p_(i) denotes polarity switch signal at time i(w_(i) = p_(i) + p_(i−1), + denotes XOR)

By pulsing and/or relaxing the write current 1408 as shown in FIG. 14,the pulse-based writer 144 may enable the formation of magnets inmagnetic media more efficiently or with less distortion to data inneighboring tracks.

System-On-Chip

FIG. 15 illustrates an exemplary System-on-Chip (SoC) 1500 that mayimplement various aspects of pulse-based writing for magnetic storagemedia. The SoC 1500 may be implemented in any suitable device, such as asmart-phone, netbook, tablet computer, access point, network-attachedstorage, camera, smart appliance, printer, set-top box, server,solid-state drive (SSD), magnetic tape drive, hard-disk drive (HDD),storage drive array, memory module, storage media controller, storagemedia interface, head-disk assembly, magnetic media pre-amplifier,automotive computing system, or any other suitable type of device (e.g.,others described herein). Although described with reference to a SoC,the entities of FIG. 15 may also be implemented as other types ofintegrated circuits or embedded systems, such as an application-specificintegrated-circuit (ASIC), memory controller, storage controller,communication controller, application-specific standard product (ASSP),digital signal processor (DSP), programmable SoC (PSoC),system-in-package (SiP), or field-programmable gate array (FPGA).

The SoC 1500 may be integrated with electronic circuitry, amicroprocessor, memory, input-output (I/O) control logic, communicationinterfaces, firmware, and/or software useful to provide functionalitiesof a computing device or magnetic storage system, such as any of thedevices or components described herein (e.g., hard-disk drive). The SoC1500 may also include an integrated data bus or interconnect fabric (notshown) that couples the various components of the SoC for datacommunication or routing between the components. The integrated databus, interconnect fabric, or other components of the SoC 1500 may beexposed or accessed through an external port, parallel data interface,serial data interface, peripheral component interface, or any othersuitable data interface. For example, the components of the SoC 1500 mayaccess or control external storage media or magnetic write circuitrythrough an external interface or off-chip data interface.

In this example, the SoC 1500 is shown with various components thatinclude input-output (I/O) control logic 1502 and a hardware-basedprocessor 1504 (processor 1504), such as a microprocessor, processorcore, application processor, DSP, or the like. The SoC 1500 alsoincludes memory 1506, which may include any type and/or combination ofRAM, SRAM, DRAM, non-volatile memory, ROM, one-time programmable (OTP)memory, multiple-time programmable (MTP) memory, Flash memory, and/orother suitable electronic data storage. In some aspects, the processor1504 and code (e.g., firmware) stored on the memory 1506 are implementedas a storage media controller or as part of a storage media interface toprovide various functionalities associated with pulse-based writing formagnetic storage media. In the context of this disclosure, the memory1506 stores data, code, instructions, or other information vianon-transitory signals, and does not include carrier waves or transitorysignals. Alternately or additionally, SoC 1500 may comprise a datainterface (not shown) for accessing additional or expandable off-chipstorage media, such as magnetic memory or solid-state memory (e.g.,Flash or NAND memory).

The SoC 1500 may also include firmware 1508, applications, programs,software, and/or operating system, which may be embodied asprocessor-executable instructions maintained on the memory 1506 forexecution by the processor 1504 to implement functionalities of the SoC1500. The SoC 1500 may also include other communication interfaces, suchas a transceiver interface for controlling or communicating withcomponents of a local on-chip (not shown) or off-chip communicationtransceiver. Alternately or additionally, the transceiver interface mayalso include or implement a signal interface to communicate radiofrequency (RF), intermediate frequency (IF), or baseband frequencysignals off-chip to facilitate wired or wireless communication throughtransceivers, physical layer transceivers (PHYs), or media accesscontrollers (MACs) coupled to the SoC 1500. For example, the SoC 1500may include a transceiver interface configured to enable storage over awired or wireless network, such as to provide a network attached storage(NAS) device with pulse-based writing features.

The SoC 1500 also includes a read/write channel 142 and a pulse-basedwriter 144, which may be implemented separately as shown or combinedwith a storage component or data interface. Alternately or additionally,the SoC 1500 may include interfaces to a pre-amplifier and spindle/motorassembly of a magnetic media disk drive. As described herein, thepulse-based writer 144 may insert transitions into pre-amp data, alterbit polarities, manage a control signal (e.g., for masking), relax writecurrent, configure various bit or current thresholds, or any combinationof the like to implement aspects of pulse-based writing for magneticstorage media. Any of these entities may be embodied as disparate orcombined components, as described with reference to various aspectspresented herein. Examples of these components and/or entities, orcorresponding functionality, are described with reference to therespective components or entities of the environment 100 of FIG. 1 orrespective configurations illustrated in FIG. 2, and/or FIG. 3. Thepulse-based writer 144, either in whole or part, may be implemented asdigital logic, circuitry, and/or processor-executable instructionsmaintained by the memory 1506 and executed by the processor 1504 toimplement various aspects or features of pulse-based writing formagnetic storage media.

The SoC 1500 also includes a read/write channel 142 and a pulse-basedwriter 144, which may be implemented separately as shown or combinedwith a storage component or data interface. Alternately or additionally,the SoC 1500 may include interfaces to a pre-amplifier and spindle/motorassembly of a magnetic media disk drive. As described herein, thepulse-based writer 144 may insert transitions into pre-amp data, alterbit polarities, manage a control signal (e.g., for masking), relax writecurrent, configure various bit or current thresholds, or any combinationof the like to implement aspects of pulse-based writing for magneticstorage media. Any of these entities may be embodied as disparate orcombined components, as described with reference to various aspectspresented herein. Examples of these components and/or entities, orcorresponding functionality, are described with reference to therespective components or entities of the environment 100 of FIG. 1 orrespective configurations illustrated in FIG. 2, and/or FIG. 3. Thepulse-based writer 144, either in whole or part, may be implemented asdigital logic, circuitry, and/or processor-executable instructionsmaintained by the memory 1506 and executed by the processor 1504 toimplement various aspects or features of pulse-based writing formagnetic storage media.

The pulse-based writer 144, may be implemented independently or incombination with any suitable component or circuitry to implementaspects described herein. For example, a pulse-based writer may beimplemented as part of a DSP, processor/storage bridge, I/O bridge,graphics processing unit, memory controller, storage controller,arithmetic logic unit (ALU), or the like. The pulse-based writer 144 mayalso be provided integral with other entities of SoC 1500, such asintegrated with the processor 1504, memory 1506, a storage mediainterface, or firmware 1508 of the SoC 1500. Alternately oradditionally, the pulse-based writer 144, and/or other components of theSoC 1500 may be implemented as hardware, firmware, fixed logiccircuitry, or any combination thereof.

As another example, consider FIG. 16 which illustrates an examplestorage media controller 1600 in accordance with one or more aspects ofpulse-based writing for magnetic storage media. Generally, the storagemedia controller 1600 enables the computing device 102 to accesscontents of magnetic storage media, such as an operating system,applications, or data for applications or other services. The storagemedia controller may also write and read data of the computing device102 to and from the magnetic storage media with which the controller isassociated.

In various aspects, the storage media controller 1600 or any combinationof components thereof may be implemented as a storage drive controller(e.g., HDD controller or HDD chipset), storage media controller, NAScontroller, storage media interface, storage media endpoint, storagemedia target, or a storage aggregation controller for magnetic storagemedia, solid-state storage media, or the like (e.g., hybrid SSD/HDDstorage systems). In some cases, the storage media controller 1600 isimplemented similar to or with components of the SoC 1500 as describedwith reference to FIG. 15. In other words, an instance of the SoC 1500may be configured as a storage media controller, such as the storagemedia controller 1600 to manage magnetic storage media. In this example,the storage media controller 1600 includes input-output (I/O) controllogic 1602 and a processor 1604, such as a microprocessor,microcontroller, processor core, application processor, DSP, or thelike. The storage media controller also includes a host interface 1606(e.g., SATA, PCIe, NVMe, or Fabric interface) and a storage mediainterface 1608 (e.g., magnetic media interface or head-disk assembly(HDA) interface), which enable access to a host system (or fabric) andstorage media, respectively. In this example, the storage mediainterface includes separate instances of a spindle interface 1610 and apre-amp interface 1612, such as to enable communication with a head-diskassembly of a media drive.

In some aspects, the storage media controller 1600 implements aspects ofpulse-based writing for magnetic storage media when managing or enablingaccess to storage media that is coupled to the storage media interface1608. The storage media controller 1600 may provide a storage interfacefor a host system via the host interface 1606, through which storageaccess commands, such as data to write to the magnetic storage media arereceived from the host system. As shown in FIG. 16, the storage mediacontroller 1600 may also include a servo control unit 140, read/writechannel 142, and a pulse-based writer 144. The servo control unit 140 isoperably coupled to the spindle interface 1610 and may provide spindleor voice coil control for a magnetic media drive. In this example theread/write channel 142 and pulse-based writer 144 are operably coupledto the pre-amp interface 1612 and may provide pre-amp data (e.g.,modified NRZ bit patterns or waveforms) and/or pulse-writing controlsignals to pre-amplifier circuitry (or pulse-based writing circuitry ofthe pre-amplifier) of the media drive. In some aspects, the processor1604 and firmware or logic of the storage media controller 1600 areimplemented to provide various data writing or processingfunctionalities associated with pulse-based writing for magnetic storagemedia.

The pulse-based writer 144 of the storage media controller 1600 may beimplemented separately as shown or combined with the processor 1604,read/write channel 142, or storage media interface 1608. In accordancewith various aspects, the pulse-based writer 144 may insert transitionsinto pre-amp data, alter bit polarities, manage a control signal (e.g.,for masking), relax write current, configure various bit or currentthresholds, or any combination of the like. Examples of these componentsand/or entities, or corresponding functionality, are described withreference to the respective components or entities of the environment100 of FIG. 1 or respective configurations illustrated in FIG. 2 and/orFIG. 3. The pulse-based writer 144, either in whole or part, may beimplemented as processor-executable instructions maintained by memory ofthe controller and executed by the processor 1604 to implement variousaspects and/or features of pulse-based writing for magnetic storagemedia.

Although the subject matter has been described in language specific tostructural features and/or methodological operations, it is to beunderstood that the subject matter defined in the appended claims is notnecessarily limited to the specific examples, features, or operationsdescribed herein, including orders in which they are performed.

What is claimed is:
 1. A method comprising: determining that a string ofdata bits having a same polarity corresponds to a magnet formed on amagnetic storage media has a magnet length that exceeds a magnet lengththreshold associated with a magnetic media writer; asserting, inresponse to the determining, a signal to the magnetic media writer toprevent a transition in the string of data bits from causing themagnetic media writer to increase write current applied to a write headof the magnetic media writer; inserting, into the string of data bits,at least one transition to a polarity opposite to the same polarity ofthe string of data bits; and transmitting, to the magnetic media writer,the string of data bits including the at least one transition to causethe magnetic media writer to reduce an application of write currentapplied to the write head while writing the magnet corresponding to thestring of data bits to the magnetic storage media.
 2. The method ofclaim 1, wherein transmitting the string of data bits that includes theat least one transition causes the magnetic media writer to terminatethe application of the write current to the write head after writing atleast a portion of the magnet and prior to applying other write currentto the write head to write another magnet.
 3. The method of claim 2,wherein terminating the application of the write current comprisestransitioning a pre-amplifier of the magnetic media writer to anoff-state or a pre-bias voltage state prior to applying the other writecurrent to the write head to write the other magnet.
 4. The method ofclaim 1, wherein the inserting comprises inserting the at least onetransition into the string of data bits at a predetermined bit locationreferenced from at least one of: a last data bit in the string of databits having the same polarity; an end of the magnet to which the stringof data bits corresponds; or a length of the magnet to which the stringof data bits corresponds.
 5. The method of claim 1, wherein the at leastone transition comprises: a first transition to the polarity opposite tothe same polarity of the string of data bits; and a second transitionsubsequent to the first transition to the same polarity of the string ofdata bits.
 6. The method of claim 1, wherein the at least one transitioncomprises a first set of one or more transitions, and the method furthercomprises: deasserting, subsequent to the transmission of the first setof one or more transitions in the string of data bits, the signal to themagnetic media writer; inserting, into the string of data bits, a secondset of one or more transitions that includes a transition to the samepolarity of the string of data bits; and transmitting, to the magneticmedia writer, the string of data bits including the first set of one ormore transitions and the second set of one or more transitions, thesecond set of one or more transitions causing the magnetic media writerto pulse the write current applied to the write head while writing themagnet corresponding to the string of data bits to the magnetic storagemedia.
 7. The method of claim 1, wherein the string of data bits havinga same polarity includes at least three bits of non-return-to-zero (NRZ)or at least three bits of non-return-to-zero inverted (NRZi) encodeddata bits.
 8. The method of claim 1, wherein the magnet length thresholdis a predefined threshold associated with or based on a geometry of thewrite head; and the determining that the string of data bits correspondsto the magnet having the length that is longer than the magnet lengththreshold includes comparing a consecutive number of the data bitshaving the same polarity to the magnet length threshold.
 9. An apparatuscomprising: an interface to receive data from a host; a disk of magneticstorage media to store the data; a magnetic media writer configured towrite, via a write head of the magnetic media writer, the data to themagnetic storage media as respective magnets that correspond to databits of the data; and a write current controller configured to:determine that a string of the data bits having a same polaritycorresponds to a magnet having a length that is longer than a magnetlength threshold associated with the magnetic media writer; assert, inresponse to the determination, a signal to the magnetic media writer toprevent the magnetic media writer from increasing write current appliedto the write head in response to a transition in the string of databits; insert, into the string of data bits, at least one transition to apolarity opposite to the same polarity of the string of data bits; andtransmit, to the magnetic media writer, the string of data bitsincluding the at least one transition to cause the magnetic media writerto reduce an application of write current applied to the write headwhile writing the magnet corresponding to the string of data bits to themagnetic storage media.
 10. The apparatus of claim 9, wherein thetransmission of the string of data bits that includes the at least onetransition causes the magnetic media writer to terminate the applicationof the write current to the write head after writing at least a portionof the magnet and prior to application of write current to the writehead to write another magnet to the magnetic storage media.
 11. Theapparatus of claim 9, wherein the write current controller is furtherconfigured to: insert the at least one transition into the string ofdata bits at a predetermined bit location referenced from at least oneof: a last data bit in the string of data bits having the same polarity;an end of the magnet to which the string of data bits corresponds; or alength of the magnet to which the string of data bits corresponds. 12.The apparatus of claim 11, wherein the predetermined bit location in thestring of data bits comprises: at least four data bits from the lastdata bit in the string of data bits having the same polarity; at leastfour magnet periods from the end of the magnet to which the string ofdata bits corresponds; or at least for magnet periods from a terminatingpoint of the length of the magnet to which the string of data bitscorresponds.
 13. The apparatus of claim 9, wherein the at least onetransition comprises a first set of one or more transitions, and thewrite current controller is further configured to: deassert, subsequentto the transmission of the first set of one or more transitions in thestring of data bits, the signal to the magnetic media writer; insert,into the string of data bits, a second set of one or more transitionsthat includes a transition to the same polarity of the string of databits; and transmit, to the magnetic media writer, the string of databits including the first set of one or more transitions and the secondset of one or more transitions, the second set of one or moretransitions causing the magnetic media writer to pulse the write currentapplied to the write head while writing the magnet corresponding to thestring of data bits to the magnetic storage media.
 14. The apparatus ofclaim 13, wherein: the application of the write current to the writehead includes a baseline quantity of write current; and the pulse ofwrite current applied to the write head comprises an overshoot quantityof write current that includes a sum of the baseline quantity of writecurrent and another quantity of write current of a same polarity as thebaseline quantity of write current.
 15. The apparatus of claim 9,wherein: the magnet length threshold is a predefined thresholdassociated with or based on a geometry of the write head; and todetermine that the string of the data bits corresponds to the magnethaving the length that is longer than the magnet length threshold, thewrite current controller is further configured to compare a consecutivenumber of the data bits having the same polarity to the magnet lengththreshold.
 16. A System-on-Chip comprising: an interface to a host fromwhich data is received for writing to magnetic storage media; aninterface to a media writer of the magnetic storage media; a writecurrent controller implemented at least partially in hardware, the writecurrent controller configured to: determine that a string of data bitshaving a same polarity corresponds to a magnet formed on the magneticstorage media has a length that is longer than a magnet length thresholdassociated with the media writer; assert, in response to thedetermination, a signal to the media writer to prevent the media writerfrom increasing write current to a write head of the media writer inresponse to a transition in the string of the data bits; insert, intothe string of data bits, at least one transition to a polarity oppositeto the same polarity of the string of data bits; and transmit, to themedia writer, the string of data bits including the at least onetransition to cause the media writer to reduce an application of writecurrent applied to the write head while writing the magnet correspondingto the string of data bits to the magnetic storage media.
 17. TheSystem-on-Chip of claim 16, wherein the transmission of the string ofdata bits that includes the at least one transition causes the mediawriter to terminate the application of the write current to the writehead after writing at least a portion of the magnet and prior to anotherapplication of write current to the write head to write another magnet.18. The System-on-Chip of claim 17, wherein the write current controlleris further configured to: insert the at least one transition into thestring of data bits at a predetermined bit location referenced from atleast one of: a last data bit in the string of data bits having the samepolarity; an end of the magnet to which the string of data bitscorresponds; or a length of the magnet to which the string of data bitscorresponds.
 19. The System-on-Chip of claim 16, wherein the at leastone transition comprises a first set of one or more transitions, and thewrite current controller is further configured to: deassert, subsequentto the transmission of the first set of one or more transitions in thestring of data bits, the signal to the media writer; insert, into thestring of data bits, a second set of one or more transitions thatincludes a transition to the same polarity of the string of data bits;and transmit, to the media writer, the string of data bits including thefirst set of one or more transitions and the second set of one or moretransitions, the second set of one or more transitions causing the mediawriter to pulse the write current applied to the write head whilewriting the magnet corresponding to the string of data bits to themagnetic storage media.
 20. The System-on-Chip of claim 19, wherein: theapplication of the write current to the write head includes a baselinequantity of write current; and the pulse of write current applied to thewrite head comprises an overshoot quantity of write current thatincludes a sum of the baseline quantity of write current and anotherquantity of write current of a same polarity as the baseline quantity ofwrite current.